The present invention is related to establishing a data path from a channel to an I/O adapter in a data processing system having a network fabric, and is more particularly related to obtaining multiple port addresses by a fibre channel directly from the network fabric.
A host Fibre Channel adapter supporting multiple logical partitions (LPARs) or other entities which are executing the Fibre Channel/SCSI (FCP) protocol must have a unique Fibre Channel N_Port address identifier for each LPAR supported. However, there is no existing method by which an adapter with a single Fibre Channel N_Port can obtain multiple N_Port address identifiers directly from the fabric F_Port.
The need to obtain multiple (virtual) N_Port identifiers is a new requirement which arises when multiple host LPARs sharing the same Fibre Channel adapter, execute the SCSI/Fibre Channel protocol (FCP) through a single N_Port. It is advantageous to minimize the number of adapters to reduce cost and to maximize adapter utilization. Others have not solved this problem previously.
There are other protocols which result in an N_Port having more than one ID, such as when an N_Port receives multicast frames (sent to a multicast address) as well as frames sent to its own N_Port address. These other protocols are specifically designed for unique purposes (such as multicast), however, and they require the presence of supporting “servers” in the fabric (e.g. the Multicast Server). They also have limitations which result from the specific function provided. For example, multicast addresses are shared by all N_Ports in the multicast group, but an address used by a logical partition must only be useable by that logical partition.
Another potential method of obtaining another N_Port ID could be achieved by allowing the N_Port to log in multiple times with the fabric, but this would require initialization of flow-control buffers, and would therefore disrupt the operation of preexisting virtual N_Ports with other N_Port Ids.
U.S. Pat. No. 5,276,813 issued Jan. 4, 1994 to Elliott et al. for ACQUIRING ADDRESSES IN AN INPUT/OUTPUT SYSTEM, discloses a computer Input/Output system in which link-level facilities issue an acquire link address frame when initially coming on line. A dynamic switch receiving the frame then assigns a link address to the link-level facility.
U.S. Pat. No. 5,420,988 issued May 30, 1995 to Elliott for ESTABLISHING LOGICAL PATHS THROUGH A SWITCH BETWEEN CHANNEL AND CONTROL UNITS IN A COMPUTER I/O SYSTEM, discloses a mechanism for assigning multiple logical path identifications with a single physical path.
U.S. Pat. No. 6,084,859 issued Jul. 4, 2000 to Ratcliff et al. for INTERNET PROTOCOL ASSISTS USING MULTI-PATH CHANNEL PROTOCOL, discloses an apparatus for allowing any initiating host to establish communications with any receiving host in a computing network using a multi-path channel communication protocol.